My partner, Shana does not want to feed onion bagels to rats because she heard onions are toxic to dogs (with poisoning occurring in quantities larger than a cup.) I can't seem to find any information on their effects on rats. If rats do experience toxicity at a similar comparable level to dogs, a small bite of onion bagel should not be harmful. BUT I have no evidence that their toxicity is similar, OR that they are even toxic to rats. So what I'm hoping for is:

A good website that lists toxic substances to rats, ALONG WITH the lethal dose and safe dose. A scientific website would be ideal. or failing to find that, A list of toxic substancesor failing to find that, Anecdotal evidence from people who've fed onions and onion-containing food to their rats.

Generally, if you would eat a food, you can give it to your rats. Here are some exceptions and notables: raw dry beans or peanuts—contains antinutrients that destroy vitamin A and enzymes needed to digest protein and starches, and causes red blood cells to clumpraw sweet potato—contains compounds that form cyanide in the stomach green bananas—inhibits starch-digesting enzymesgreen potato skin and eyes—contain solanine, a toxinwild insects—can carry internal parasites and diseasesraw bulk tofu—can contain bacteria, packaged raw tofu is safeorange juice—forbidden for male rats only, d-limonene in the skin oil, which gets into the orange juice during squeezing, can cause kidney damage and kidney cancer due to a protein that only male rats have in their kidneys. Pieces of the orange fruit are okay if you wash the orange-skin oil off of it after peeling it.

Foods to Feed with Caution carbonated beverages—rats can’t burp (but they can fart!)

Dried corn can contain high levels of fungal contaminates which has been shown to cause liver cancer in rats. Corn also contains high levels of both nitrates and amines. These two compounds can combine in the stomach to form nitrosamines which are carcinogenic. Other foods high in nitrates include beets, celery, eggplant, lettuce, cucumber, radishes, spinach, collards and turnip greens. Therefore, I suggest you limit the amount of these foods in your rat’s diet. Some fresh corn is fine, but if you feed your rats blocks, try to avoid brands which have corn as the first ingredient.

Do be careful with raw onion. My dog went through a horrible bout of autoimmune hemolytic anemia and the only thing we could trace it to was, possibly, raw onion. It nearly killed him and his immune system was destroyed.